Vehicle builders have been using serial communication (multiplexing) between controllers to share information and distribute control for some time. Doing so has greatly reduced the amount of cross-vehicle signal wiring in the vehicle's electrical distribution system (EDS) needed to implement the comfort, convenience, and safety features desired in modern vehicles.
However, not much has been done to simplify the power and ground distribution part of the EDS. Batteries and alternators (power sources) are usually used to provide power to the vehicle. To distribute the power, the positive side of the power source is connected to fuse blocks that are located in the engine compartment or the passenger compartment of the vehicle. The fuse blocks serve as distribution points for power feed to devices, e.g., actuators, sensors and control elements. The fuse blocks also house the protection devices, circuit breakers and fuses, for the power feeds. The minus side of the power source is often connected to the metal components of the vehicle (body, chassis, engine block, etc.) which then serve as the ground return path from all of the active elements.
Control of the devices in the vehicle to implement desired features is divided into controllers by function or by location (engine, navigation, passenger seat, driver seat, door, etc.). The controller in each of the zones shares information with other controllers using a shared-access serial bus. The bus usually follows an industry standard such as J1850, CAN, MOST. Multiple, independent busses may be used. In that case, one of the controllers acts as a gateway for information between the incompatible busses. Each make and model of vehicle tends to have a unique collection of controllers and devices. Vehicle manufactures also tend to use proprietary serial busses. As a result, each vehicle's EDS must be uniquely designed. Even though many signal wires have been saved by using serial busses, there is another opportunity to improve the efficiency of the EDS if power and ground distribution is dealt with as well.
An alternative architecture introduces the idea of dividing the vehicle into geographic regions and locating a single controller for all of the features in that region. This architecture may also include the concept of smart peripherals to reduce the number of interconnections in localized areas of the vehicle. The smart peripherals use simple serial communication busses such as Local Interconnect Network (“LIN”) to relay information from sensors to the zone controller or to accept actuator commands from the zone controller. The zone controllers also act as power and ground distribution points for the smart peripherals.
Another alternative architecture incorporates a junction block that can be located in various zones of the vehicle. The junction block provides a mechanical and electrical connection point for power, ground and communication for small devices that are used to interface to input and output devices. The junction block also provides over current protection devices for the small connected devices, and multiple power sources distributed at different levels within the system.
Existing power, ground and control distribution architectures, while offering elements of flexibility, still require vehicle specific wiring harnesses and rigid power distribution structure and control. Moreover, these existing structures have not addressed signal wiring complexity in localized areas. Thus there is needed a flexible power, ground and control distribution architecture for the entire vehicle that is also adaptable to localized areas of the vehicle.